Brianroulstonite is a rare calcium borate, typically colorless to white. It is a very rare in residues from halite-sylvite evaporites. It was first described from Penobsquis evaporite deposit, near Sussex, New Brunswick, Canada.
Is this brianroulstonite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch brianroulstonite with a known reference. Brianroulstonite sits at Mohs ~5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: cleaveable, micaceous.
Often confused with
Brianroulstonite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside brianroulstonite
Minerals reported to co-occur with brianroulstonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₃B₅O₆(OH)₇Cl₂·8H₂O
- Mohs hardness
- ~5
- Density
- 1.97 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Cleaveable, micaceous
- Cleavage
- On {010}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Very rare in residues from halite–sylvite evaporites
Where rockhounds find brianroulstonite
Classic worldwide localities
- Penobsquis evaporite deposit, near Sussex, New Brunswick, Canada
Field-hunting tip
Where it forms: Very rare in residues from halite–sylvite evaporites. If you start seeing halite, hilgardite, pringleite in float, you are in the right ground. Typical habit: cleaveable, micaceous. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify brianroulstonite?+
Where is brianroulstonite found?+
What rocks look like brianroulstonite?+
What minerals are found with brianroulstonite?+
What kind of rock does brianroulstonite form in?+
What is brianroulstonite used for?+
Find brianroulstonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
